There has long been a need for an improved system for handling human wastes in portable and certain fixed individual toilet systems, for example, toilet systems in boats, recreational vehicles, temporary portable toilets provided for construction and outdoor entertainment sites, camping facilities, and the like. Many of these present systems use disinfectant and/or deodorant chemicals to treat the waste to render it less offensive. These systems however still result in an accumulation of odorous and unpleasant sludge which must eventually be handled and transported, dumped into a sewage system, or otherwise finally disposed.
Chemical fixation and solidification processes for wastes have found recent favor for detoxifying human wastes and for producing solid waste having physical properties suitable for ultimate disposal in landfills, ocean dumping, and the like. The use of sanitary landfills is one of the major current methods for final disposal of sludge and incinerator ash resulting from the processing of sewage. Stabilized sludge containing no free water can be satisfactorily disposed in a sanitary landfill either along or in a mixture with municipal solid waste under current regulations. A sanitary landfill is managed so that wastes are systematically deposited and covered with earth to control environmental impacts within predefined limits. However, prior to placing sludge from the processing of human waste in a landfill, it is necessary that the waste be sufficiently dewatered or stabilized to minimize the quantity of free water present. Also, there are requirements that leachant and runoff from sanitary landfills must be minimized and when necessary collected and suitably treated to prevent pollution of ground and surface waters.
Certain waste solidification methods are known in the art. For example, U.S. Pat. No. 3,837,872 discloses a two-part cement-liquid silicate method for treating the liquid waste by adding an aqueous solution of an alkali metal silicate and a silicate setting agent, which converts the waste into a chemically and physically stable solid end product. This method is clearly effective in treating human waste, but suffers the disadvantage that the system requires the controlled introduction of the solidification chemicals in two parts at particular times in the treatment process.
In my co-pending application Ser. No. 510,152, filed June 3, 1983 now abandoned, which is incorporated herein by reference and made a part hereof, I disclose a method for treating aqueous liquid and semi-liquid waste by solidification by mixing a dry water-reactive solidification agent comprising cement, a dry water absorbent material, and a powdered alkali metal silicate to the waste to convert the admixture into a chemically and physically solid end product which contains virtually no free-standing water. With the advent of this system, which uses ingredients which are all dry powders and can be premixed, packaged, and stored, there is now available a solidification technology which can be satisfactorily employed in the context of a system for the treatment of human waste on site.
In order to employ such a solidification system for use in a portable or mobile toilet system, a number of requirements must be met. The mechanical components of the system must be compact and lightweight. The cost of the system should be roughtly equivalent to existing commercial units presently used, such as in boats, airplanes, and recreational vehicles. Additionally, it is important that the solidified waste produced be easily disposable into normal solid waste processing channels. For example, it would be desirable if the waste could be placed in conventional garbage processing services provided by many municipalities and commercial services. Inasmuch as such garbage processing facilities currently handle items such as disposable diapers which are not disinfected prior to disposal, a disinfected solidified waste is safer and should be more acceptable than nontreated disposable diapers.
It is also important that the solidification system be simple and relatively foolproof. Preferably, the chemicals employed for solidification should be pre-packaged in an easy-to-dispense form, such as in a throw-away packet. Accordingly, the solidification chemicals should be relatively nonhazardous, and at worse no more hazardous than common household chemical products.
Finally, the solidified block of waste produced by the system should preferably be containerized to minimize the unpleasantries associated with handling or removing the waste. Moreover, the solid waste should be easily removable from the toilet system.